[llvm] r213917 - [X86] Clarify some stackmap shadow optimization code as based on review
Lang Hames
lhames at gmail.com
Thu Jul 24 19:29:19 PDT 2014
Author: lhames
Date: Thu Jul 24 21:29:19 2014
New Revision: 213917
URL: http://llvm.org/viewvc/llvm-project?rev=213917&view=rev
Log:
[X86] Clarify some stackmap shadow optimization code as based on review
feedback from Eric Christopher.
No functional change.
Modified:
llvm/trunk/lib/Target/X86/X86AsmPrinter.h
llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
Modified: llvm/trunk/lib/Target/X86/X86AsmPrinter.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86AsmPrinter.h?rev=213917&r1=213916&r2=213917&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86AsmPrinter.h (original)
+++ llvm/trunk/lib/Target/X86/X86AsmPrinter.h Thu Jul 24 21:29:19 2014
@@ -44,16 +44,27 @@ class LLVM_LIBRARY_VISIBILITY X86AsmPrin
~StackMapShadowTracker();
void startFunction(MachineFunction &MF);
void count(MCInst &Inst, const MCSubtargetInfo &STI);
+
+ // Called to signal the start of a shadow of RequiredSize bytes.
void reset(unsigned RequiredSize) {
RequiredShadowSize = RequiredSize;
CurrentShadowSize = 0;
- Count = true;
+ InShadow = true;
}
+
+ // Called before every stackmap/patchpoint, and at the end of basic blocks,
+ // to emit any necessary padding-NOPs.
void emitShadowPadding(MCStreamer &OutStreamer, const MCSubtargetInfo &STI);
private:
TargetMachine &TM;
std::unique_ptr<MCCodeEmitter> CodeEmitter;
- bool Count;
+ bool InShadow;
+
+ // RequiredShadowSize holds the length of the shadow specified in the most
+ // recently encountered STACKMAP instruction.
+ // CurrentShadowSize counts the number of bytes encoded since the most
+ // recently encountered STACKMAP, stopping when that number is greater than
+ // or equal to RequiredShadowSize.
unsigned RequiredShadowSize, CurrentShadowSize;
};
Modified: llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86MCInstLower.cpp?rev=213917&r1=213916&r2=213917&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86MCInstLower.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86MCInstLower.cpp Thu Jul 24 21:29:19 2014
@@ -66,7 +66,7 @@ static void EmitNops(MCStreamer &OS, uns
namespace llvm {
X86AsmPrinter::StackMapShadowTracker::StackMapShadowTracker(TargetMachine &TM)
- : TM(TM), Count(false), RequiredShadowSize(0), CurrentShadowSize(0) {}
+ : TM(TM), InShadow(false), RequiredShadowSize(0), CurrentShadowSize(0) {}
X86AsmPrinter::StackMapShadowTracker::~StackMapShadowTracker() {}
@@ -80,7 +80,7 @@ namespace llvm {
void X86AsmPrinter::StackMapShadowTracker::count(MCInst &Inst,
const MCSubtargetInfo &STI) {
- if (Count) {
+ if (InShadow) {
SmallString<256> Code;
SmallVector<MCFixup, 4> Fixups;
raw_svector_ostream VecOS(Code);
@@ -88,16 +88,17 @@ namespace llvm {
VecOS.flush();
CurrentShadowSize += Code.size();
if (CurrentShadowSize >= RequiredShadowSize)
- Count = false; // The shadow is big enough. Stop counting.
+ InShadow = false; // The shadow is big enough. Stop counting.
}
}
void X86AsmPrinter::StackMapShadowTracker::emitShadowPadding(
MCStreamer &OutStreamer, const MCSubtargetInfo &STI) {
- if (Count && CurrentShadowSize < RequiredShadowSize)
+ if (InShadow && CurrentShadowSize < RequiredShadowSize) {
+ InShadow = false;
EmitNops(OutStreamer, RequiredShadowSize - CurrentShadowSize,
TM.getSubtarget<X86Subtarget>().is64Bit(), STI);
- Count = false;
+ }
}
void X86AsmPrinter::EmitAndCountInstruction(MCInst &Inst) {
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